Lake Athabasca (French: lac Athabasca, from Woods Cree: ãthapãskãw) is located in the northwest corner of Saskatchewan and the northeast corner of Alberta between 58° and 60° N. The lake covers 7,850 km²; (3,030 sq mi), is 283 km (175 mi) long, has a maximum width of 50 km (31 mi), and a maximum depth of 243 m (797 ft), and holds 204 cu km (49 cu mi) of water, making it the largest and deepest lake in both Alberta and Saskatchewan, and the eighth largest in Canada. Water flows northward from the lake via the Slave River and Mackenzie River systems, eventually reaching the Arctic Ocean. Fort Chipewyan, the oldest European settlement in Alberta, is located on the small western shore of the lake, where the Slave River begins its northward journey alongside the eastern boundary of Wood Buffalo National Park.


Uranium and gold mining along the northern shore resulted in the birth of Uranium City, Saskatchewan, which was home to the mine workers and their families. While the last mine closed in the 1980s, the effects of mining operations have heavily contaminated the northern shores.

The Lake Athabasca Sand Dunes, the largest active sand dunes in the world north of 58°, are adjacent to the southern shore. After a long struggle with government bureaucracy and opposition from mining companies, the dunes were designated a "Provincial Wilderness Park" in 1992.

Lake Athabasca contains 23 species of fish, with a world record lake trout of 46.3 kg (101.8 lb) having been caught from its depths in 1961 by means of a gillnet..